Background

Purine nucleoside phosphorylase (PNP) deficiency accounts for about 4% of severe combined immunodeficiency diseases. PNP deficiency is a variable disease with recurrent infections and neurodevelopmental delay. Autoimmunity and malignancy can still occur in one-third of patients.

Methods

Case report.

Case Presentation

An 8-year-old Saudi female who was apparently healthy presented at the age of 7 years with confirmed systemic lupus erythematosus (SLE) and lupus nephritis that were poorly controlled with conventional therapy. She also had frequent sinopulmonary and varicella infections. Preliminary immunological workup showed severe lymphopenia and depressed lymphocyte proliferation assay. The uric acid was within normal levels at 179 μmol/L (normal range, 150 to 350 μmol/L) 6 weeks after blood transfusion. Genetic study revealed a homozygous missense mutation c.265G>A in the PNP gene, resulting in a substitution of glutamic acid to lysine at amino acid 89 of the encoded protein (E89K). The PNP serum level was 798 nmol/h/mg (normal level 1354 ± 561 nmol/h/mg) 6 weeks after blood transfusion. Hematopoietic stem cell transplantation (HSCT) was planned from a matched unrelated donor; however, she developed an EBV and varicella meningoencephalitis. Atypical malignant cells suggestive of lymphoma were discovered, likely induced by EBV, and suspicious lesions were shown on brain MRI and PET scan. Unfortunately, she passed away before HSCT due to multiorgan failure.

Conclusion

This report emphasizes the challenges in recognizing PNP deficiency in a patient suffering from SLE.

中文翻译：

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嘌呤核苷磷酸化酶缺乏症合并迟发性系统性红斑狼疮和淋巴瘤一例。

背景

嘌呤核苷磷酸化酶 (PNP) 缺乏症约占严重联合免疫缺陷病的 4%。PNP 缺乏症是一种反复感染和神经发育迟缓的可变疾病。三分之一的患者仍可发生自身免疫和恶性肿瘤。

方法

案例报告。

案例展示

一名 8 岁沙特女性，7 岁时确诊为系统性红斑狼疮 (SLE) 和狼疮性肾炎，常规治疗控制不佳。她还经常发生窦肺和水痘感染。初步免疫学检查显示严重的淋巴细胞减少和淋巴细胞增殖抑制。输血6周后尿酸在正常水平179 μmol/L（正常范围，150～350 μmol/L）。遗传研究揭示了PNP 中的纯合错义突变 c.265G>A基因，导致在编码的蛋白质 (E89K) 的氨基酸 89 处谷氨酸被赖氨酸取代。输血后 6 周 PNP 血清水平为 798 nmol/h/mg（正常水平 1354 ± 561 nmol/h/mg）。造血干细胞移植 (HSCT) 计划从匹配的无关供体进行；然而，她患上了 EBV 和水痘脑膜脑炎。发现提示淋巴瘤的非典型恶性细胞，可能由EBV诱导，脑MRI和PET扫描显示可疑病变。不幸的是，由于多器官功能衰竭，她在 HSCT 之前就去世了。

结论

本报告强调了识别 SLE 患者 PNP 缺乏的挑战。